A selective NIR-emitting zinc sensor by using Schiff base binding to turn-on excited-state intramolecular proton transfer

An environmentally sensitive zinc-selective two-photon NIR fluorescent turn-on probe and zinc sensing in stroke

A two-photon near infrared (NIR) fluorescence turn-on sensor with high selectivity and sensitivity for Zn2+ detection has been developed. This sensor exhibits a large Stokes' shift (∼300 nm) and can be excited from 900 to 1000 nm, with an emission wavelength of ∼785 nm, making it ideal for imaging in biological tissues. The sensor's high selectivity for Zn2+ over other structurally similar cations, such as Cd2+, makes it a promising tool for monitoring zinc ion levels in biological systems. Given the high concentration of zinc in thrombi, this sensor could provide a useful tool for in vivo thrombus imaging.

Uncovering the dependence of ESIPT behaviors and fluorescence properties of two new benzothiazole-based fluorophores on solvent polarity: A TD-DFT study

We have studied the spectral features and excited state intramolecular proton transfer (ESIPT) processes of 2-(2',4'-dihydroxyphenyl)benzothiazole (OHBT) and 2-(2'-hydroxy-5'-chlorophenyl)benzothiazole (CHBT) using density functional theory (DFT) and time-dependent density functional theory (TD-DFT). To consider the impact of solvent polarity and intermolecular hydrogen bond (H-bond) on the ESIPT behavior and photophysical properties, four solvents including toluene (TL), tetrahydrofuran (THF), methanol (MeOH) and dimethylsulfoxide (DMSO) were used. The simulated absorption and fluorescence wavelengths of OHBT and CHBT are well consistent with the experimental values. According to the results of structures, electron density and infrared (IR) vibrational frequencies, we found that the intramolecular H-bonds in OHBT/CHBT and OHBT-MeOH/CHBT-MeOH are strengthened in the first singlet excited state (S₁), which will be benefical to the ESIPT process. The potential energy curves (PECs) verified that the ESIPT processes in OHBT/CHBT and OHBT-MeOH/CHBT-MeOH can take place much easier because of their lower energy barrier. The influences of solvent polarity on ESIPT behaviors and photophysical properties of OHBT and CHBT are summarized below. As the solvent polarity becomes stronger from TL to DMSO, the energy gaps enlarges a little, the maximum absorption and fluorescence peaks at normal form red-shift slightly, and the strengths of H-bond in S₁ state become weaker, which makes the ESIPT process occur much harder. The formation of intermolecular H-bond between OHBT/CHBT and MeOH is conducive to promote the ESIPT process of OHBT/CHBT.

Autonomous Bionanorobots via a Cage-Shaped Silsesquioxane Vehicle for In Vivo Heavy Metal Detoxification

Nanorobots hold great promise for integrated drug delivery systems that are responsive to molecular triggers. Herein, we successfully developed an automatic smart bionanorobot that has transport capability and recognizes and removes zinc ions from poisoned cells based on nanoscale polyhedral oligomeric silsesquioxane molecules. This intelligent bionanorobot can easily move inside and outside the cell and find zinc ions owing to its highly selective recognition to zinc ions and high cell permeability, especially the well-combined high penetration and strong binding energy. More importantly, it was also found that this intelligent bionanorobot can restore round HeLa cells to a normal fusiform cell morphology following high-concentration zinc treatment and does not interfere with cell proliferation and division. It was also shown by in vivo experiments that the bionanorobot can inhibit persistent enlargement of the liver caused by zinc ion poisoning.

A new diformyl phenol based chemosensor selectively detects Zn2+ and Co2+ in the nanomolar range in 100% aqueous medium and HCT live cells

A new diformyl phenol based chemosensor that can sense Zn2+ and Co2+ in the nanomolar range in 100% aqueous solution and in HCT cells was explored.

The crystal structure of (E)-2-((tert-butylimino)methyl)-4-chlorophenol, C11H14ClNO

C11H14ClNO, monoclinic, P21/c (no. 14), a = 9.072(3) Å, b = 5.882(2) Å, c = 21.258(7) Å, β = 100.351°, V = 1115.9(7) Å3, Z = 4, R gt (F) = 0.0391, wR ref (F 2) = 0.1167, T = 296(2) K.

Synthesis of an unprecedented H-stitched binuclear crystal structure based on selective fluorescence recognition of Zn2+ in newly synthesized Schiff base ligand with DFT and imaging application in living cells

Single hydrogen atom stitched giant binuclear crystal.

Self-agglomerated crystalline needles harnessing ESIPT and AIEE features for the ‘turn-on’ fluorescence detection of Al3+ ions

We report the synthesis of probe 2 for the fluorescence “turn-on” detection of Al³⁺ ions in CH₃OH.

Terpyridine derivatives as “turn-on” fluorescence chemosensors for the selective and sensitive detection of Zn2+ ions in solution and in live cells

A terpyridine based compound L1 was designed and synthesized as an “off–on” chemosensor for the detection of Zn²⁺.

A theoretical investigation on excited-state single or double proton transfer process for aloesaponarin I

The excited-state proton transfer (ESPT) dynamical behavior of aloesaponarin I (ASI) was studied using density functional theory (DFT) and time-dependent DFT (TDDFT) methods. Our calculated vertical excitation energies based on TDDFT reproduced the experimental absorption and fluorescence spectra well [Nagaoka et al. J. Phys. Chem. B, 117, 4347 (2013)]. Two intramolecular hydrogen bonds were confirmed to be strengthened in the S1 state, which makes ESPT possible. Herein, the ESPT process is more likely to happen, along with one hydrogen bond (O1–H2⋯O3). Qualitative analyses about charge distribution further demonstrate that the ESPT process could occur because of the intramolecular charge transfer. Our constructed potential energy surfaces of both S0 and S1 states show that a single proton transfer reactive is more reasonable along with the intramolecular hydrogen bond (O1–H2⋯O3) rather than O4–H5⋯O6 in the S1 stated potential energy surface. Then, ASI-SPT* decays to the ground state with a 640 nm fluorescence; subsequently, the ASI-SPT form shows that reverse ground state single-proton transfer back to the ASI structure occurs. Particularly, dependent on relatively accurate potential energy barriers among these excited-state stable structures, we confirmed the excited-state single proton transfer process rather than using the controversial nodal plane model.

Small heterocycles as highly luminescent building blocks in the solid state for organic synthesis

ESIPT photoactive mono-formylated benzoxazole derivatives obtained through a Duff functionalization protocol using a simple synthetic methodology.

A novel 2-(2′-aminophenyl)benzothiazole derivative displays ESIPT and permits selective detection of Zn2+ ions: experimental and theoretical studies

Synthesis of a novel 2-(2′-aminophenyl)benzothiazole based probe (1) and demonstration of excited state intramolecular proton transfer (ESIPT) with a large Stokes shift (∼246 nm) are presented.

A highly selective, sensitive and reversible fluorescence chemosensor for Zn2+ and its cell viability

A new ligand (H2L) was synthesized and designed for sensing properties. H2L shows fluorescence ‘switch ON’ with Zn²⁺ ions with a detection limit of 1.47 μM. The H2L and 1 showed marginal toxicity against MCF-7 and A375 cell lines.

A novel fluorescent chemosensor based on tetra-peptides for detecting zinc ions in aqueous solutions and live cells

A novel fluorescent chemosensor (HL) based on tetra-peptides conjugated with dansyl groups has been designed and synthesized, which is a promising analytical tool for detecting Zn²⁺ in aqueous solutions and live cells.

A novel peptide-based fluorescent chemosensor for measuring zinc ions using different excitation wavelengths and application in live cell imaging

A novel peptide-based fluorescent chemosensor containing both tryptophan and a dansyl fluorophore has been designed to detect Zn²⁺ in 100% aqueous solution and living cells via two pathways including fluorescence resonance energy transfer and chelation enhanced fluorescence.

A single molecular probe for multi-analyte (Cr³⁺, Al³⁺ and Fe³⁺) detection in aqueous medium and its biological application

An ESIPT based fluorescent sensor 1 was developed, which could selectively detect and differentiate trivalent metal ions Cr(3+), Al(3+) and Fe(3+) in aqueous medium. The cell imaging experiments confirmed that 1 can be used for monitoring intracellular Cr(3+) and Al(3+) levels in living cells.

A Benzothiazole-Based Sensor for Pyrophosphate (PPi) and ATP: Mechanistic Insight for Anion-Induced ESIPT Turn-On

A benzothiazole derivative 2 bearing two 2,2'-dipicolylamine (DPA) groups was examined for its zinc-binding and subsequent anion sensing properties. The study revealed the anion sensing mechanism of polyphosphate anions via sequential binding to two zinc centers, on the basis of both 1H NMR and mass spectral evidences. The mechanistic insight would provide valuable information for the future design of new excited state intramolecular proton transfer (ESIPT) sensors. In addition, the zinc complex exhibited the solvent-switchible selectivity, responding to pyrophosphate (PPi) in EtOH but adenosine 5'-triphosphate (ATP) in water.

NIR sensing of Zn(ii) and subsequent dihydrogen phosphate detection by a benzothiazole functionalized ninhydrin based receptor

Zn²⁺ responsive (NIR) benzothiazole functionalized ninhydrin based receptor selectively sense H₂PO₄⁻ ion.